Continuous vulcanizing method and apparatus



Jam 1, 1952 G. E. BERGGREN 2,581,230

Y CONTINUOUS VULCNIZING METHOD AND APPARATUS Filed June 19, 1948 2Sl'EETS--SHET l I TTORA/E Jan' 1, 1952 G. E. BERGGREN 2,581,230

CONTINUOUS VULCANIZING METHOD ANO APPARATUS Filed June 19, 1948 2sHEETs-sms2T 2 G. E BERGGRE/V Arrow/EV Patented Jan. l, 1952 CONTINUOUSVULCANIZIN G METHOD AND APPARATUS George E. Berggren, Baltimore, Md.,assignor ,to Western Electric Company, Incorporated, New York, N. Y.,. acorporation of New York Application June 19, 1948', Serial'Nm 34,056 20claims; (o1. ifs-6) This invention relates to continuous vulcanizingmethods and apparatus, and more particularly to methods of and apparatusfor Vulcanizing coverings of vulcanizable material upon continuouslyadvancing conductors.

In the manufacture Vof insulated lamentary articles such as insulatedand jacketed conductors and cables, a core having an ,outer covering ofvulcanizable compound therearound is advanced through an elongatedv.vulcanizing tube containing a high temperature vulcanizing mediumunder high pressure, such as 'high pressure steam, to vulcanize thecovering on the core. Frequently, the core vmay include a layer oftextile material such as a cotton serving or a braided or knitted cottoncovering. In vthat case, the vulcanization of the outer .covering often`develops high internal pressure in entrapped pockets of air andmoisture withinthe textile layers vwhich must be reduced materiallybefore Athe core emerges into the atmosphere in order nto preventblistering of the resulting vulcanized cover.- ing.

This is generally accomplished by passing a core and its vulcanizedcovering directly into an elongated coolingtubesupplied with a lowtemperature cooling medium, `such as cold water. under pressure for thepurpose of `cooling the covering until the internal pressures within thecovering have been reducedv to` values such .that there 4is no danger ofthe cover blistering when it emerges into the atmosphere. Variousdevices have been proposed for useat the junction point of thevulcanzing tube yand .the .cooling tube to maintain the .escape .of thevulcanizing medium from .the vulcanizing tube ata minimum becauseexcessive leakage of the high temperature vulcanizing medium into thecoo'lingytube raises the temperature of the cooling medium and therebyimpairs the efficiency of ,the cooling medium. Also, it is desirable -tominimize the. lossl of heat from the vulcanizing medi-um. To hold-theleal;- age of the yulcanizing medium to aminimum, the pressure of thecooling medium must ibeymaintained substantially equal to the-pressureof the vulcanizing mediumfat all times.

An `object of the invention is `to provide new and improved methods ofand -aplalatusrfor vulcanizing coverings surroundingcontinuously-advancing cores. Y Y

A further object of the invention is to :provide new and improved-vu1oaoizinemethodoendopparatus employing a vulcanizingtube and accolingtube, and new end effective mevtliodsv` and meansv for maintaining. `thepressure'yof the .water in. the cooling tube substantially equal to thepressure of the vulcanizing medium in the vulcanizing tube at all times.

Apparatus Vembodying certain features of the invention, by means ofwhich methods embodying certain features of the invention may bepracticed, Acomprises an elongated .tube through -vvhich `a continuouslyadvancing core having a vulcanizable covering thereon may be passed,means for supplying a high temperature, high pressure fluid to a portionof the tube first encountered by the core to vulcanize the covering onthe core, means for supplying a vlow temperature cooling fluid toportion of the tubo ,Subsequently encountered by the advancing core tocool the vulcanized covering as it `emerges from the-vulcanizing fluid,and means responsive to a temperature differential -vexisting at remotepoints in `the cooling fluid for maintaining the pressure of the coolingfluid and the vulcanizing lfluid substantially in equilibrium at alltimes.

A complete understanding or the invention may sulating coverings oncontinuously advancing lamentary cores in accordance with one embodimentof the invention;

Fig. 2 is a perspective view showing a continuation of the apparatusshown in Fig. 1 extending from the left-hand end thereof;

l Fig. 3 is an enlarged fragmentary side Yelevation of the portion of'the apparatus shown vin Fig.2;

Fig. 4 is an enlarged vertical vsectional View taken along line B- ofFig, 3j, and

Fig. Y5 is an enlarged verticalsection taken along line 5-5 of Fig. 3.

Referring now in detail to the drawings and more particularly .to Fig.l. .a .lamorltary C011- duotor I0 is beine withdrawn from a rotatablylmounted supply reel H and' around a guide pulley I2 by va motor drivencapstan yi 5, which is turning at a constant rate of speed in acounterclockwise direction. The conductor Ill passes around the capstanI5 and l.then through, an extruding head lr6, forming partof an extruderi7, which extrudes a .vulcanizable covering around the conductor IU toforma coveredconductor in- Y dicated by thefnurneralz.

Uponfleaving .the extruding head It, the c overed conductor passes intoan elongated vulcanizing tube indicated generally at 22 which consistsof a steam tube 23, a tubular jacket 24 surrounding the tube 23, and aninsulating jacket 25 surrounding the jacket 24. High pressure, hightemperature steam is admitted to the steam tube 23 by means of a pipe 26whereby the entire tube 23 is lled with high pressure steam. Steam at alower pressure is admitted to the jacket 24 surrounding the tube 23 toheat the steam tube 23.v

The vulcanizing tube 22 (Fig. 1.) joined to the extruding head I6 in asuitable manner and conl tinues therefrom through a housing enclosing ahigh voltage sparktester 21 (Fig. 1), and through a housing enclosing anair wiper 28 toan elongated enclosure 30. The covered conductor 2Upasses through the elongated .vulcanizing .tube 22, and upon emergingtherefrom passes directly through a splice box 3 I, an elongated coolingtube indicated generally at 32 and a pressure reducing nozzle 33 intothe atmosphere. Low temperature water under high pressure is admitted tothe cooling tube 32 by a pipe 34 for the purpose of cooling thepreviously vulcanized covering of the covered conductor 28. Upon leavingthe nozzle 33, the conductor 20 passes around an idler pulley 36 andthen travels along a V-shaped trough to which a continuous stream ofcold Water is supplied by a pipe 4l. A pipe 42 is connected to thetrough 40 adjacent to the air wiper 28 to drain the water from thetrough.

The conductor 20 passes from the trough 40, through the air wiper 28,which removes the moisture from the vulcanized covering, and thentravels along a second V-shaped trough t0 the sparktester 2'! where thecovering on the conductor is subjected to a high voltage testingoperation. The conductor then passes around an idler pulley 46, whichguides the conductor 2b to a capstan 5B turning at a constant rate ofspeed in a clockwise direction. The conductor 26 passes around thecapstan 59 several times and then around a pulley 5| mounted on adistributing apparatus, indicated generally at 52, which is driven by amotor 53. The distributing apparatus 52, 7

including the pulley 5l, distributes the conductor 2t evenly on one orthe other of motor driven takeup reels -55.

The takeup reels 55-55 are provided for the f'purpose of permittingcontinuous reeling of the covered conductor 20, A second supply4 reel 51containing a conductor identical with the conductor I0, and a secondguide pulley 58 are provided for the purpose of maintaining a supply offilamentary conductor which will permit a substantially continuousextruding and vulcanizing process.

The covering on the conductor 20, in passing through the steam tube 24of the vulcanizing tube 22, is subjected to sufficient heat and pressureto vulcanize the covering. However, if a textile covering is presentbeneath the vulcanized covering, undesirable high internal pressures maybe developed in entrapped pockets of air and moisture within the textilecovering during the vulcanization of the outer covering. In order toprevent these high internal pressures from blistering the vulcanizedcovering when the conductor emerges into the atmosphere, the conductcr23 passes directly from the steam tube:

through the cooling tube 312 filled with low temperature water underpressure, which serves to cool the covering whilekeeping the coveringunder pressure and reduces the internal pressuresn I within thecoverings to values such that .therel substantially equal to thepressure or" the steam in the vulcanizing tube in order to prevent excessive escape of steam therefrom into the cooling tube. Such leakage ofsteam results in raising the temperature of the cooling water above itsmost eifective operating temperature and in loss of high temperaturesteam from the Avulcanizing tube. The steam admitted to the steam tube23 y issubject to substantial fluctuation in pressure :steam pressuresubstantially over sustained periods of operation and it is '-necessary,therefore, to maintain the pressure of the water in the cooling tubesubstantially equal to the pressure of the steam in the steam tube atall times.

Anelectronic controller indicated generally at 60 (Fig. 2) iselectrically connected to resistance bulbs 6| and B2 positioned in thecooling tube 32. The controller B0 and the bulbs 6l and B2 are providedfor the purpose of maintaining the water in the cooling tube at apressure determined by the differential existing in the temperatures ofthe cooling water at the temperature Ibulbs due to a particularoperating temperature and pressure of the steam. When the pressures ofthe Water and steam are substantially equal, a definite temperaturedifferential exists in the cooling water between the bulbs 6l and 82 dueto a normal leakage of steam from the vulcanizing tube 22 into thecooling tube 32 and the transfer of heat from the vulcanized covering ofthe conductor 28 to the water as the conductor passes therethrough. Thetemperature differential in the cooling water may be held substantiallyconstant for such balanced pressure conditions by circulating the lowtemperature water through the cooling tube 32 at a rate commensuratewith the pressure and temperature of the steam. The

vcombination of the heating effect of the con- .the pressure of thesteam is subject to fluctuation,

requires a iiexible pressure control system capable of maintaining thewater pressure and the in equilibrium throughout long periods ofoperation.

The temperature controller 50 includes a sensitive Wheatstone bridgecircuit in which the resistance bulbs 6I and 62 are connected and anelectronic circuit for amplifying any unbalance potential occurringacross the bridge circuit. The amplified potential is utilized torebalance the bridge circuit and in so doing to actuate an air bleedervalve of the controller to vary the output air pressure of thecontroller which is used for controlling an air-operated valveregulating the pressure of the water admitted to the cooling tube 32.Each temperature diierential existing between the resistance bulbs 6land 62 calls for a different balance of the bridge circuit and a corresponding operating position of the air bleeding valve.

One type of such a controller is manufactured by the Foxboro Company,Foxboro, Mass. and is described in detail in their book No. 644 entitledTemperature Controller on pages 1 and 2, identied as 16-300 and datedFebruary 1945, pages 1 and 2, ldentied as 11-449 and dated February tube1947, pages 1 and 2, identified as 16--3001-and dated May 1947, pages 1and 2, identied as 13- 150 and dated February 1947, pages l and 2,idenvtiied as l1-452 and dated October 1946, pages 1 and i2, identiiiedas 11-460 and dated October 1946, pages 1- and 2, identified as ll-eland dated April 1946, pages l, 2 and 3, identified as -1l462, and datedJuly 1947. A schematic `diagram of s-uch a controller is shown in mycepending application Seriai No. 37,1583, nled Julyl, 1948. In View ofthe description contained in the abovementioned book, adetaileddescription-oi the construction and operation of the controllerSe is unnecessary.

Referring now to Fig. 3 of the draw-ings, it wil be noted that thecooling tube 32 comprises a tubular body de' and an `elongated tubularmember ed connectedso as to communicate with the tubular body. ri'h-ecooling tube 32 has its righ-t end Vconnected to the adjacent end .oithe splice box 3l so as to communicate therewith, and the left endthereof is connected so as to communicate with the nozzle 33. Thetubular body has a baled tube 73 positioned in the entrance end thereofthrough which the conductor 2S passes in traveling from the splice box.3l into the tubular body 33 of the cooling tube. 32. The tube 73prevents sudden increases in the pressure of the steam in thevulcanizing tube from causing the steam to surge into the cooling tube32 and force a substantial amount of. Water therefrom through the nozzle33, and also prevents the Water in the cooling tube from surging intothe splice box upon substantial decreases in the pressure of the steam.The baffled tube E3 is fully described and claimed in my co-pendingapplication Serial No. 17,916, led March V30, 1943, hence a moredetailed description of the seal is not necessary herein. v

The tubular body 63 (Fig. V3) is provided with a partition 84 positionedintermediate the ends of the body Which partition is provided with agland 85 centrally secured to the partition by means of a nut 86. Agland do is mounted in a centr-al bore provided Vin the exit end or thetubular body 63 to substantially seal the exit end -oi'the cooling tube.Each of the glands 95 and Sii is provided with Aa central aperturethrough which the conductor passes as it travels through the coolingtube `3i, and sufficient clearance is provided -between the centralaperture and the vcovered con- `cluctor to permit passage of theconductor therethrough without scarring the covering on the conductor.

The nozzle .33 secured on the exit end-of the tubular member Slt of thecooling tube 532 consists of an elongated tubular member t2 remov- -ablysecured to the adjacent end of the tubular member 643 of the coolingtube. The tubular member 152 has a plurality `of annular baiiles S-Blipositioned therein vbetween tubular spacers .B5-4.5. The baies dfi-434are provided wi h the central apertures through which the conductor 23passes as it travels through the nozzle 33 and emerges into theatmosphere.

The provision of the bailies Elli-JSA (Fig. 3) in the nozzle 33, permitsthe water in the cooling tube 32 to escape therefrom at a substantiallylow rate of flow into the closure and at the same time gradually reducesthe pressure of the escaping water substantially to 4that of theVatmosphere. The nozzle permits a continuous circulation of the coolingwater admitted through the pipe v34A` through the entire length. of thecooling 32'., whereby the'cooling water may bemain`A cent to thecontrollerA tained at" its :most'lefective yoperating temperature. Thecooling Water discharged from the end 'of the-nozzle 33 into the closure3d, is drained from the closure 3E by-a pipe 97 to a large drain 923.The drain 93 may return the Water to a suitable Water cooling system,and then the cooled `vvater may be recirculated through the water.cooling system including the cooling tube 32.

The resistance bulb 6l (Fig. 5) is positioned adjacent to the right endof the tubular body 63 of the cooling tube 32 .so that the portion to beimmersed in the cooling water is directly in the path oi the incomingwater supplied to the vcooling tube by the pipe 34. The resistance bulbA62 (Fig. 4) is positioned adjacent to the left end oi the tubular bodyS3 of the cooling tube 32 and measures the temperature of the Waterafter it has circulated through the tubular body. The resietance bulbs6l and lb2 .are identical in yconstruction and have vthe same electricalcharacteristics, hence vonly the resistance bulb El Will be ldescribedin detail.

y.- terminal head H30 (Fig. 5) is provided .Von the outer end of theresistance bulb Si by means oi' which the bulb is connected electricallyto the controller 60. The terminal head- |06 is secured to av bodyportion lill which threadedly engages Ia boss ISE provided in thetubular body. A thin shell $95 is secured to the threaded body lill andhas the i'ree end thereof sealed so Aas to completely enclose asensitive resistance element (not shown) positioned ,therein LowVtemperature water, under a pressure substantially higher than themaximum pressure which may be reached by the steam in the vulcanizingtube 22 is conducted from a suitable supply source by a pipe l I (Fig.3) to a reducing .valve Hi arranged to be actuated by an air diaphragmllt. The -air diaphragm H2 receives air under constant pressure from anair supply pipe H3 which actuates t-he diaphragm H2 and sets the openingof the valve Ill so that it produces a constant Water. pressure in thepipe H5, Which pressure is still -above the maximum pressure of thesteam in the vulcanizing tube. The pipe l l5 conducts the water leavingthe valve i i-i to a reducing valve -l i6 arranged to 'be actuated .byian air vdiaphragm .H7 which receives air under a pressure controlled bythe controller 69 through a pipe 20, The valve HS is connected to thecooling tube 32 by the pipe 34, Whereby the Water emerging from the pipeiid, after being subjected to a further reduction in pressure by thevalve H3 in accordance with the air pressure applied on its diaphragm lil by the controller 3G, then is conducted to the Acooling tube 32,. Airis supplied to the temperature controller ofrom the supply `pipe l lilthrough a lter dripwell l2i and a pipe E22.

The steam in the splice box 3l (Fig. 3) `and the Water from the body S3of the cooling tube :eo-ntact each other at the entrance end of the:baffled tube 13, whereby the area in the splice box `adjacent to theentrance end of the tube 'I3 contains a condensate consisting vof lowtemperature steam and hot Water. A rpipe 123 is connected to the bottomof the splice box 3i -to conduct this condensate from the splice lbox tola drain vpot v24, and from the drain pot through a pipe 126 to a drainvalve 21 arranged to discharge the condensate from the splice box into adrain pipe vl2!! at a predetermined rate.

A water pressure gauge E32 is mounted adja- (iii for indicating thepres- .sure-.of the water in the supply pipe '34 and the 7 cooling tube32. A pressure gauge 33 is also positioned adjacent to the controller 80for indicating the pressure of steam in the steam tube 23 of thevulcanizing tube 22.

Operation Let it be assumed that the conductor I has been threadedthrough the apparatus from the supply reel il to one of the takeup reels55-55. that the vulcanizing tube 22 is lled with high pressure, hightemperature steam, that the cooling tube 32 is filled with lowtemperature water. and that the controller 60, in response to the temperature diierential between the bulbs 6l and 62, has adjusted theopening of the valve l I6 so that the pressure of the water in thecooling tube is substantially equal to the pressure of the steam in thevulcanizing tube and the splice box. The capstans l and 50 then areplaced in operation to draw the conductor through the apparatus, inwhich case, the covered conductor 20 emerges from the extruding head I6of the extruder ll and passes through the vulcanizing tube 22, Where thecovering is subjected to heat and pressure suicient to vulcanize thecovering. During the vulcanization of the covering there may developundesirable high internal pressures in entrapped pockets of air andmoisture within the covering. The conductor and the vulcanized coveringthen pass through the cooling tube 32, whereby the Vulcanized coveringis cooled so as to reduce the internal pressures in the entrappedpockets of air and moisture to Values such that there is no danger ofthe covering blistering when the conductor 20 emerges from the nozzle 33into the atmosphere.

As the apparatus operates with the pressure of the steam and the watersubstantially equal, there is a minimum leakage of steam through thebaffled tube 13 into the cooling tube 32 as the conductor passes throughthe tube. This leakage of steam into the cooling tube together with theheat transfer between the vulcanized covering and the water creates atemperature difierential in the cooling water surrounding the resistancebulbs 6I and 52 positioned in the tubular body 63 of the cooling tube32. This temperature diierential between the bulbs 6I and 62 causes thecontroller` 60 to maintain an air pressure on the diaphragm lll of thevalve H6 which sets an opening of the valve suicient to maintain thepressure of the water in the cooling tube substantially equal to thepressure of the steam in the vulcanizing tube. At the same time, thisopening of the valve H6 maintains a circulation of water through thecooling tube and nozzle at a rate commensurate with the temperature andpressure of the steam in the vulcanizing tube. The rate at which thewater circulates through the cooling tube 32 under the pressure set bythe controller maintains the heating effect that the steam and the heattransfer from the vulcanized covering have on the water within safelimits so that the water in the cooling tube is maintained at its mosteffective operating temperature at all times.

As long as such balanced operating conditions prevail between the steamand water pressures, the controller maintains this control of the valveSIB, in which case the temperature differential between the bulbs 6l and62 will remain substantially constant. Since the steam in thevulcanizing tube 22 is subject to substantial variations in pressureover long periods, the

controller B0, in response to a temperature differential produced by agiven steam pressure, continuously maintains the pressure of the waterin the cooling tube substantially equal to the pressure of the steam inthe vulcanzing tube.

Let it be assumed that a sudden increase in the pressure of the steam inthe vulcanizing tube 22 occurs. This increase in the pressure of thesteam increases. the leakage of steam through the baiiled tube 13 intothe tubular body 63 as the conductor 20 passes through the tube 13. Thisincreased leakage of the steam through the tube 'I3 raises thetemperature of the Water in the cooling. tube, and if this conditionwere allowed to prevail for a prolonged period of time, the temperatureof the Water would reach a point at which the vulcanized covering 2liwould not be cooled sufdciently in passing through the cooling tube. Asa result, the high internal pressures developed within the coveringduring the vulcanization thereof would not be reduced to safe values,and when the covered conductor emerges into the atmosphere, blisteringof the covering would occur. The water heated by the increased leakageof steam into the tubular body circulates through the right-half of thetubular body and strikes the partition 84 which causes a mixing of theheated water with the low temperature water lining the wall of thetubular body. This heated water then' passes through the centralaperture oithe gland 85 with the conductor 20 and mixes with the Waterin the left-half of the tubular body and nally increases the temperatureof the water surrounding the shell M15 of the bulb 62. It should benoted that the resistance bulb 6l is positioned directly in the path ofthe incoming water from the pipe 34 and is, therefore, substantiallyunaffected by the increased leakage of the steam from the vulcanizingtube and the increase in the temperature of the Water in the tubularbody 63.

The increase in temperature of the water surrounding the bulb 62increases the temperature differential of the cooling Water contactingthe bulbs 6l and 62, which immediately necessitates an adjustment of thebridge circuit of the electronic controller 5U, which in turn increasesthe air pressure applied on the diaphragm l Il of the valve H6. Thisincreased air pressure on the diaphragm I Il' increases the opening ofthe valve H6, and thereby permits an increased pressure and rate of flowof Water in the cooling tube 32. The initial increase in the opening ofthe valve I IE is sufficient to raise the pressure of the water in thecooling tube slightly above the increased steam pressure in thevulcanizing tube, in which case there occurs a decreased leakage ofsteam into the tubular body and a gradual decrease in the temperaturedifferential of the cooling water surrounding the bulbs. The controller60, in response to the decreasing temperature differential in thecooling water, effects a corresponding decrease in the opening of thevalve l I6. However, the controller 6U cannot restore the initialtemperature differential that existed inthe cooling water in the tubularbody prior to the increase in the steam pressure due to the increasedheating effect of the steam and the vulcanized covering on the water inthe cooling tube, resulting from the increased temperature of the steamwhich occurs Wih the increase in the steam pressure.

This combined increased heating effect on the Water in the tubular bodycreates a slightly increased operating temperature of the water in thetubular body, and consequently a slight increase in the temperaturediierential between 6| and 82,. effects an opening of thevalye l i6 so.as

to. maintain pressure. of the water substantially equal tothe pressureof thesteam, in which case minimum leakage. of steam into thel coolingtube occurs. The.- apparatus. continues to operate under the increasedsteam. pressure and. water pressure, whereby the cooling watereiectively reduces the intern-al pressures within. the vulcanizedcovering to values such that there is nodanger of the cover blisteringwhen thel conductor emerges from the nozzle 33 into the` atmosphere.

Should a sudden decrease in the pressure of the steam occur, it wouldVresult in the. apparatus operating momentarily with the pressure of thewater in the cooling tube substantially exceeding` the pressure of thesteam of the vulcanizing tube. Under such circumstances, thecoolingwater forces its way through, the baffledtube 13 and enters thesplice. box 3l where it contacts the steam therein and creates. asubstantial increase in the condensation of the steam w-ithin the splicebox. The condensate collecting in the splice box is drained oi atapredetermined rate by the drain valve |21 to the pipe 128. Since thewater pressure exceeds the steam. pressure, there is no leakage of thesteam from the vulcanizing tube into the cooling tube and the heatingeffect. on the water by such leakage isnot present inthe cooling tube.The absence of the heating eiect by the steam, allows the entirefbody ofwater in the. cooling tube. 32 to assume a somewhat vlower temperatureas thewater circulates through the cooling tube, and the shell L85v ofthe bulb 62 is eventually surrounded by water of a lower temperature.

As a result, there occurs al decrease in the temperature differential ofthe. water surrounding the bulbs El and 62, which causes the electroniccontroller to eect a reduced air pressure on the diaphragm Hl of thevalve IIB. The reduced air pressure on the. diaphragm Il-'l reduces theopening of the valve and thereby reduces the pressure of the water inthe cooling tube, and, consequently, the rate at which the cooling watercirculates through the cooling tube. The initial regulation of thevValve H6 by the controller 6!! is such that. the steam pressure nowslightly exceeds the pressure of the water, whereby leakage ofsteam-from the vulcanizing tube through the bellied tube 'I3 into the.cooling tube 32. again takes place causing the temperature of the. waterin the cooling tube to increase slightly and thereby in. crease thetemperature differential of the. water surrounding the bulbs 6| and 62.While the leakage of steam into the cooling tube causes a .gradualincrease in the temperature differential measured by the bulbs,v the,temperature diierential that existed prior to the decrease in the steampressure will not be attained due to the decreased temperature of the.steam and the vulcanized covering of. the conductor 2U.

The electronic controller 6U, in response to the gradually increasingtemperature differential of the cooling water at the bulbs (il and 62,continuously increases the opening of the. valve IIB until a temperaturediierential exists which regulates the valve so that the pressure of thewater equals the new and lower steam pressure. When the controller Bfinally balances the water pressure with the new steam pressures, thereresults a lower operating temperature dilerential vof the cooling waterat. the `bulbs 6I. and. 62 than that which existedv prio-r to. the.reduction in the pressure. of the steam and minimum leakage. of steaminto the cooling tube, whereby thev water is maintained at its most,eiective operating temperature. Since the controller 6.a continuouslymaintains the pressure of the water substantially equal to the pressureof the steam, blistering of the covering will not occur whilethe.covering is being cooled by the water in thecooling tube nor when theconductor emerges from the nozzle 33. into theatmosphere.

To maintain such a control or the water pressure with respect. to. thesteam pressure, the controller is initially adj-usted so that for anygiven steam pressure. and resulting temperature dii ierential in thecooling water surround-ing the bulbs tl and the pressure of. the waterin the cooling tube is maintained slightly under the pressure of the.Ysteam in the vulcanizing tube so that there is always present a. normalbut minimum leakage of steam into the cooling tube. This. is due to thefac-t that. it is preferable to have the leakage occur from thevulcanizing tube to the cooling tube, rather than the reverse'condition, .because the amount of steam condensed under these conditionsis at a minimum, and, hence, the steam. consumption of the apparatus isaccurately regulated so as; to maintain a. high degree of efeienc-y inthe; operation of the apparatus.

Inoperating conti'nuousvulcanizing apparatus like thatdescribedhereinaboveriit has been found that. a steam pressure of atleast 15d pounds. per square inch in the vulcanizingtube willsatisfactori-ly vfulcanizey the covering on the conductor advancingtherethrough. Under certain operating conditions established by the sizeof the. conductor andthe rate at which it travels through thevulcanizi-ngy tube, itv has .been found that a vulcanizing tubeapproximately 200 feet long having steam under a pressure. of 250poundsl per squarey inch willv prove satisfactory. With such a steampressure, the water in the supply line is maintained at a pressure of270 pounds per square inch to allow for fluctuations in the steampressure.` The valve H, in response to the cont-roller 6B, lreduces thepressure of the water admitted to the cooling tube so that it issubstantially equal to the. pressure of the steam at all times. Undervthese conditions, it has been found that, when the. cooling tube 32 isapproximately sixteen feet long and the nozzle 33 is approximatelythree. feet long, the apparatus will cool the covering and reduce theinternal pressures entrapped therein so that danger of the coveringblistering after it has passed through the cooling tube is prevented.

The vulcanizing tube 22, the splice box 3l, the cooling tube 32 and thenozzle 33 have been described as separate elements for the purpose ofsimplifying the specification and for emphasizing the particularfunction each element performs in the treatment of the insulatedconductor 20. The vulcanizing tube 22 comprises a plurality of lengthsof pipe to form a vulcanizing tube having a predetermined length. Thesplice box 3l is interposed between the exit end of the vulcanizing tubeand the entrance end of the cooling tube to provide a closure which maybe opened when the conductor l0 is threaded from the extruding headl'through the vulcanizing tube and cooling tube. vSince these. elementsprovide a continuous chamber in which the conductor is enclosed from thetime it leaves the extruding head I6 until it emerges from the nozzle33, the entire assembly could be considered as a single tube having asteam-lled portion sufficiently long to vulcanize the covering on thecore I0, and a water filled portion sufficiently long to cool thecovering before it emerges into the atmosphere.

What is claimed is:

l. An ap-paratus for the continuous vulcanization of a vulcanizablecovering surrounding a continuously advancing core, which comprises anelongated tube through which the covered core passes continuously, meansfor supplying a high temperature, high pressure vulcanizing fluid to theportion of the tube first encountered by the core to vulcanize thecovering on the advancing core, means for supplying a low temperaturecooling fluid under pressure to a portion of the tube subsequentlyencountered by the core to cool the vulcanized covering, said fluidsmeeting at a point intermediate the ends of the tube whereby the coolingfluid is subject to a heat gain from the vulcanizing fluid that varieswith diiferences between the pressures of the nuids and effectscorresponding temperature differentials between different points in thecooling fluid, means for measuring the temperatures at predeterminedspaced points within the cooling uid, and means responsive to thetemperature differentials between said spaced points in the cooling uidas measured by said temperature measuring means for maintaining thepressurps of the vulcanizing fluid and the cooling fluid substantiallyequal.

2. An apparatus for the continuous vulcanizing of a vulcanizablecovering surrounding a continuously advancing core, which comprises anelongated tube through which the covered core passes continuously, meansfor supplying a high temperature, high pressure vulcanizing fluid to aportion of the tube first encountered by the advancing core as it passesthrough the tube to vulcanize the covering thereon, means for supplyinga low temperature cooling fluid under pressure to a portion of the tubesubsequently encountered by the core as it passes through the tube tocool the vulcanized covering, said fluids meeting at a pointintermediate the ends of the tube whereby the cooling fluid is subjectto a heat gain from the vulcanizing fluid that varies with differencesbetween the pressures of said fluids and effects correspondingtemperature differentials between different points in the cooling fluid,temperature-sensitive elements immersed in the cooling fluid at spacedpoints in the cooling portion of the tube, and an electronic controllerconnected to the temperature-sensitive elements and responsive todifferences in the temperatures of those portions of the cooling iiuidsurrounding the temperature-sensitive elements as measured by thoseelements for maintaining the pressures of thevulcanizing uid and thecooling fluid substantially equal.

3. An apparatus for the continuous vulcanizing of a vulcanizablecovering surrounding a continuously advancing core, which comprises anelongated tube through which the advancing covered core passescontinuously, meansfor supplying high temperature, high pressure steamto a portion of the tube first encountered by the core as it passestherethrough to vulcanize the covering thereon, means for supplying lowtemperature cooling water under pressure to a portion of the tubesubsequently encountered by the core to cool the vulcanized covering,said water being in heat exchange contact with the. Stream i' 12 wherebythe water is subject to a heat gain from the steam that varies withdifferences between the pressures of the Water and the steam and effectscorresponding temperature diierentials between spaced points in thecooling water, a temperature-sensitive element subject to thetemperature of the cooling water at the entrance end of the coolingportion of the tube, a second ternperature-sensitive element subject tothe temperature of the water at a point in the cooling portion of thetube removed from the firstmentioned temperature-sensitive element, andan electronic controller connected to the temperature-sensitive elementsand responsive to the temperature diierentials existing in thecoolingwater surrounding the temperature-sensitive elements as measuredby those elements for maintaining the pressure of the cooling watersubstantially equal to the pressure of the steam;

4. An apparatus for the continuous vulcanization of a vulcanizablecovering surrounding a continuously advancing core, which comprisesmeans for subjecting the covering on `the advancing core to a hightemperature, high pressure vulcanizing vapor to vulcanize the covering,

means for subjecting the vulcanized covering to a high pressure, lowtemperature cooling liquid as it emerges from said vulcanizing vapor tocool the vulcanized covering, said vulcanizing vapor being in heatexchange contact with the cooling liquid and thereby effecting atempera.- ture differential between spaced points inv the cooling liquidthat varies with differences between the pressures of said vapor andliquid, means for measuring the temperatures at predetermined spacedpoints within the cooling liquid, and a controller actuated by thetemperature measuring means and responsive to the temperaturedifferentials existing between said spaced points in the cooling liquidfor continuously maintaining the pressures of the vulcanizing vapor andthe cooling liquid substantially equalvl 5 An apparatus for vulcanizinga vulcanizable covering surrounding a continuously advancing corewherein high internal pressures develop in entrapped pockets of air andmoisture withinl the covering upon vulcanization of the coveringthereof, which comprises means for subjecting the covering on theadvancing conductor to a high temperature, high pressure vulcanizingiiuid to vulcanize said covering, means for subjecting the vulcanizedcovering to a high pressure, low temperature cooling fluid as it emergesfrom said vulcanizing iiuid'to cool the vulcanized covering and therebyreduce the internal pressures therein to values such that there is nodanger of blistering when the conductor emerges from the cool'- ingfluid into the atmosphere, said vulcanizing uid being in heat exchangecontact with the cooling fluid and thereby effecting a temperaturedifferential in the cooling fluid between spaced points therein whichvaries with fluctuations in the pressures of the said fluids, atemperaturesensitive element positioned in the cooling uid at a pointadjacent to the contact point of the uids, a secondtemperature-sensitive element positioned'in the cooling uid at a pointremotev from the first temperature-sensitive element, and meanskresponsive to the temperature dinerentials existing between saidtemperature-sensitiveelements for maintaining the pressure of thelcooling fluid substantially equal to the pressure of the vulcanizinguid.

6. An apparatus for the vulcanization of a vlilanzabe @Wrme lilwunding acontin- 13 uously advancing ycore, which comprises an elongatedvulcanizing tube throughV which `such a covered core may be advanced,means for supplying a high temperature, high pressure vulcanizing fluidto the vulcanizing tube to vulcanize the covering onthe core, anelongated cooling t-ube connected directly to the exit end of thevulcanizing tube, means for continuously circulating a low temperaturecooling fluid under pressure through the cooling tube to cool thevulcanized covering of the core, said vulcanizing fluid being in heatexchange contact with the cooling fluid and thereby effectingdifferentials between the temperature of the water' entering the coolingtube and the temperature of the water leaving the cooling tube whichvary with fluctuations in the pressure differential between the saidfluids, means for measuring the'tez-nperatiues` of the portions of thecooling fluid entering and leaving the cooling tube,` and meansresponsive to vari-ations in the diierences between the temperaturesmeasured' by said temperature measuring means for continuouslymaintaining the' cooling iluid at a pressure which will permit only aminimum leakage of the vulcanizing iluid into the cooling tube, wherebythe cooling :duid is maintained at its most effective operatingtemperature at all times.

7. .An apparatus for the continuous vulcanization of a vulcanizablecovering surrounding a continuously advancing conductor, which comprisesan elongated vulcanizing tube through which the covered conductor may beadvanced, means for supplying high temperature, high pressure steam tothe vulcanizing tube to vulcanize the covering on the conductor, anelongated cooling tube communicating with the exit end of thevulcanizing tube, means for continuously supplying xed temperature, highpressure cooling water into the cooling tube to cool the vulcanizedcovering of the conductor as it passes therethrough, atemperature-sensitive element positioned in the cooling tube so as to besubject only to the temperature of the cooling water entering the tube,a second temperaturesensitive element positioned so as to be subject tothe tempera-ture of the water near the exit end of the cooling tube,said steam being in heat exchange contact with the water and therebycreating a temperature in the cooling water surrounding saidtemperature-sensitive elements that varies with fluctuations in thepressure differential between the steam and the water,l and meansresponsive to the temperature diferentials existing between thetemperature-sensitive elements for regulating the water supplyingy meansso as to maintain the pressure of the water substantially equal to thepressure of the steam in the vulcanizing tube, whereby minimum leakageof steam into the cooling tube occurs.

8. An apparatus for the vulcanization of a vulcanizable coveringsurrounding a continuously advancing conductor, which comprises anelongated vulcanizing tube through which suc-h 4a covered conductor maybe advanced, means for mum pressure of the steam admitted to. they vulcanizing tube, meansxfor continuously transmitting water from said.high'pressure source to the cooling tube at a point adjacent to itsconnection to the vulcanizing tube, means provide-:l in the watertransmitting means for selectively controllingl the pressure of thewater introduced into the cooling tube, a temperature-sensitiveelementsubject tothe temperature o the water entering the coolingy tube,a. second temperaturesensitive element subject to the temperature of thewater near the exit end of the cooling tube, said steam contactingtheiwater at. a point adjacent to the exit end of the vulcanizing tubeand creating'a temperature diierential in the cooling water surroundingthe temperature-sensitive elcrnents which. varies with the fluctuationsin the pressure of the steam, andan electronic controller responsive tothe temperature diiTerentials existing between those portions of thecooling water adjacent to the. temperature-sensitive elements foractuating the watery controlling means so as to maintain the waterpressure substantially equal to the steam pressure, whereby excessivesteam penetration into the cooling tube is prevented and vice' versa.

9. An apparatus for the vuloanization of a vulcanizable covering`surrounding a. continuously advancing conductor, which comprises anelongatedv vulcanizing tube. through which the covered conductorpasses', means for supplying high temperature, high but'variablepressure steam tothe vul'canizing tube for vulcanizing the coveringsurrounding the, conductor passing therethrough, a coolingtube connectedin tandem with the vul'canizing tube ythrough which the wire'passesafter it leavesI the vulcanizing tube, means for continuously supplyinglow temperature water underl high pressure to the cooling tube adjacenttoits connection to the vulcanizing tube to cool the vulcanized coveringof the conductor as it passes: therethrough, a nozzle secured to theexitend of the cooling tube through which the conductor passes forgradually reducing the pressure of the water escaping from the exit endof the cooling tube to substantially that ofv the atmosphere, atemperature-sensitive element subject to the temperature of the Water atthe entrance end of the cooling tube, a second temperature-sensitiveelement subject to the temperature ofthe water at the exit end of thecooling tube, said steam contacting the cooling water adacent to theexit end of the vulcanizing tube and' eiecting a temperaturedifferential in the cooling Water at' opposite enolsY thereof thatvariesv with fluctuation in the pressure oi the steam,l andv anrelectronic controller continuously responsive to the= temperatured'iiierentials existing between the temperature-sensitive elements toregulate the water supplying means so as to maintain the pressure of thewater inthe cooling tube substantially equal to the pressure of thesteam in the vulcanizing tube.

10. An apparatus for the vulcanization of vulcanizable coveringsurrounding a continuously advancing electrical conductor, whichcomprises an elongated vulcanized tube through which the conductorpasses, means for supplying high pressure, high temperature steam to thetube to vulcanize the covering on the conductor, an elongated coolingtube through which the moving conductor passes upon emerging from thevulcanizi'ng tube, means for continuously circulating low temperaturewaterthrough the cooling tube to cool the vulcanizedcovering of theconductor, a partition positioned intermediate the ends of the coolingtube and having a center aperture through which the water and theconductor pass for causing the Water adjacent to the walls of the tubeto mix with the water adjacent to the conductor, said steam contactingthe water adjacent to the exit end of the vulcanizing tube and effectinga temperature diierential in the cooling water at opposite ends of thecooling tube that varies with fluctuations in the pressures of the steamand the water, and means including an electronic controller responsiveto the temperature diierentials existing in the cooling water at theopposite ends of the cooling tube for maintaining the pressure ci thewater in the cooling tube substantially equal to the pres sure of thesteam in the vulcanizing tube.v

11. In an ap-paratus for the vulcanization of a vulcanizable coveringsurrounding a continuously advancing electrical conductor wherein acovered conductor passes continuously through an elongated vulcanizingtube containing high temperature, high but fluctuating pressure steam tovulcanize the covering on the conductor, the combination .with thevulcanizing tube of Aan elongated cooling tube connected in tandem withthe vulcanizing tube, a baiiied tube positioned at the entrance end ofthe cooling tube through which the conductor passes, a nozzle connectedto the exit end of the cooling tube permitting conn tinuous passage ofthe covered conductor from the cooling tube into the atmosphere, meansfor continuously circulating low temperature water under high pressurethrough 'the cooling tube from the entrance end thereof through thenozzle to cool the vulcanized covering of the conductor, a partitionpositioned intermediate the ends of the cooling tube and having acentral aperture through which the water and the conductor pass forcausing the water adjacent to the wall of the tube to mix with the wateradjacent to the ccnductor, said steam contacting the water in thebaiiled tube and effecting a temperature differential in the coolingwater at opposite ends of the cooling tube which varies withiluctuations in the pressure of the steam, a temperature-sensitiveelement subject to the temperature of the water near the entrance end ofthe cooling tube, a second temperature-sensitive element subject to thetemperature of the water near the eXit end of the cooling tube, saidtemperature-sensi tive elements being positioned on opposite sides ofsaid partition, and an electronic controller responsive to temperaturedifferentials existing between the temperature-sensitive elements forregulating the water circulating means so as to maintain the pressure ofthe water in the cooling tube substantially equal to the pressure of thesteam in the vulcanizing tube at all times, whereby excessive escape ofthe steam into the cooling tube and water into thevulcanizing tube' isprevented. l

12. An apparatus for the vulcanization of a vulcanizable coveringsurrounding a continuously advancing conductor, which comprises an elonvgated vulcanizing tube through which such a covered conductor may beadvanced, means for supplying high but fluctuating pressure, hightemperature steam to the vulcanizing tube t0 vulcanize the covering onthe advancing core, an elongated cooling tube connected to the exit endof the vulcanizing tube through which the insulated conductor passes asit emerges from the vulcanizing tube, a supply of water maintained at apredetermined low temperature and at aI pressure above the maximumpressure of the steam admitted to the vulcanizing tube, means forcontinuously transmitting water from said high pressure supply to thecooling tube adjacent to its connection with the vulcanizing tube, anair-operated valve provided in the water transmitting means forselectively controlling the water pressure in the cooling tube, saidsteam being in heat exchange contact with the cooling water adjacent tothe exit end of the Vulcanizing tube and eiecting a temperaturedifferential in the water between the temperature of the water enteringand leaving the cooling tube which varies with the fluctuations in thepressure of the steam, a resistance bulb subject only to the temperatureof the water entering the cooling tube, a second resistance bulb subjectto the temperature of the 4water near the exit end of the cooling tube,and an electronic controller responsive to temperature differentialsexisting between the resistance bulbs for controlling the air-operatedvalve so as to maintain the water pressure substantially equal to thesteam pressure.

13. The process for the vulcanization of a vulcanizable coveringsurrounding a continuously advancing electrical core, which comprisespassing the covered core continuously through a high pressure, hightemperature vulcanizing fluid to vulcanize the covering, passing thecore and its vulcanized covering continuously and directly from saidvulcanizing fluid through a cooling fluid to cool the vulcanizedcovering, measuring the temperatures of the cooling fluid at spacedpoints along the path of travel of the core through the cooling fluid,said vulcanizing fluid contacting the cooling fluid and effecting aternperature differential in the cooling fluid between the points atwhich the temperatures are measured which varies with uctuations in thepressure diierential between the said fluids, and continuouslyregulating the pressure of the cooling fluid in accordance with thetemperature differentials existing therein between the points where thetemperatures are measured to maintain the cooling fluid at a pressuresubstantially equal to the pressure of the vulcanizing` iiuid, wherebyonly a minimum escape of the vulcanizing uid into the cooling uid occursand the cooling uid is maintained at its most effective operatingtemperature,

i4. The process for the vulcanization of a vulcanizable coveringsurrounding a continuously advancing electrical conductor, whichcomprises passing the covered conductor continuously through avulcanizing zone, introducing high but fluctuating pressure steam intothe vulcanizing zone to vulcanize the covering surrounding theconductor, passing the conductor and the vulcanized coveringcontinuously and directly from said vulcanizing zone through a coolingzone, continuously introducing low temperature water u nder pressure inthe cooling zone to cool the vulcanized covering as the conductor passestherethrough, continuously measuring the temperatures of the coolingwater at spaced points in the cooling zone, said steam contacting thecooling water adjacent to the exit end ci' the vulcanizing zone andeffecting a temperature diiferential in the water between the points atwhich the temperatures are measured which varies with fluctuations inthe pressure oi the steam in the vulcanizing zone, and continuouslyregulating the pressure of the cooling water introduced into the coolingzone in accordance with the temperature differentials existing in the 17cooling water ibetween the points :where the temperatures are measuredto maintain the pressure of the coolingwater in the cooling zonesubstantially equal to the pressure of the steam in the vulcanizingzone.

15. The process for the vulcanization of a vulcanizable coveringsurrounding a continuously advancing electrical conductor in whichundesirable high internal pressures are developed in entrapped pocketsof air and moisture when the covering is vulcanized, which comprisespassing the covered conductor continuously through a vulcanizing zone,subjecting the covering to high vbut fluctuating pressure, hightemperature steam while passing through said vulcanizingv zone tovulcanize the covering, passing the conductor and the vulcanizedcovering continuously vfrom said vulcanizing zone into and through acooling zone, continuously circulating low temperature water underpressure through the cooling zone to cool the vulcanized covering,continuously measuring the temperatures of the cooling water asit entersthe cooling zone and at a point near the exit end of the cooling zone,said steam contacting the'water adjacent to the exit end of thevulcanizing zone and effecting a temperature dilTerential in the waterbetween the points at which the temperatures are measured which varieswith fluctuations in the pressure differential between the water and thesteam, and utilizing the temperature differentials existing in thecooling water between the points where the temperatures are measured tomaintain the cooling water at a pressure substantially equal to thepressure of the steam in the vulcanizing zone, whereby the internalpressures within the coverings are reduced by the cooling water tovalues such that there is no danger of the covering blistering as thevulcanized covering passes through the cooling zone.

16. An apparatus for the continuous vulcanizing of a vulcanizablecovering surrounding a continuously advancing core, which comprises anelongated vulcanizing tube through which a core having a vulcanizablecovering may be advanced, means for supplying high but iluctuatingpressure, high temperature steam to the vulcanizing tube to vulcanizethe covering on the core, an elongated cooling tube connected in tandemto the vulcanizing tube through which the covered core passes as itleaves the vulcanizing tube, means for continuously circulating highpressure water at a predetermined low temperature through the coolingtube from the entrance end to the exit end thereof to cool thevulcanized covering, an air-controlled valve for regulating the pressureof the water circulating through the cooling tube, a resistance bulbsubject only to the temperature of the water entering the cooling tube,a second resistance bulb subject to the temperature of the water nearthe exit end of the cooling tube, said steam contacting the wateradjacent to the entrance end of the cooling tube and creating atemperature differential in the cooling water between the xedtemperature of the water entering the cooling tube and the temperatureof the water near the exit end'of the cooling tube which varies with theuctuations in the pressure of the steam, and an electronic controllerresponsive to the temperature diierentials between the resistance bulbsfor regulating the air-controlled valve so as to maintain the pressureof the water in the cooling tube slightly below the pressure of thesteam in the vulcanizing tube.

17. An apparatus for'the vulcanization of a vulcanizable coveringsurrounding a continuously advancing conductor, which comprises avulcanizing tube through which a conductor having a vulcanizablecovering may be advanced, means for supplying steam atapproximately 250pounds pressure to the vulcanizing tube to vul'- canize` the covering onthe conductor, said steam being subject to sudden changesY in pressure,a cooling tube connected in tandem with the vulcanizing tube throughwhich thecovered'conductor passes as it leaves the vulcanizing'tub'e, asupply of water maintained at a predetermined low temperature and atapressure of "approximately 270 pounds per square inch, means forcontinuously circulating water from said supply through the cooling tubeto cool the vulcanized covering passing therethrough, means associatedwith the water circulating'means for selectively regulating the pressureof the water introduced into the cooling tube, a resistance bulb subjectonly to the temperature of the water asit enters the cooling tube, asecond resistance bulb subject to the temperature of the water near theexit end of the cooling tube, said steam contacting the water adjacentto the entrance end of the cooling tube and creating a temperaturediierential in the cooling water between the said resistance bulbs whichvaries with fluctuations in the steam pressure, and an electroniccontroller responsive to the temperature differentials in the coolingwater surrounding said resistance bulbs for regulating the waterpressure controlling means so as to constantly maintain a pressuredifferential between the water and the steam which permits a minimumescape of the steam into the cooling tube.

18. An apparatus for the continuous vulcanization of a vulcanizablecovering surrounding a continuously advancing core, which comprises anelongated vulcanizing tube through which the covered core may beadvanced, means for supplying high temperature, high pressure steam tothe vulcanizing tube to vulcanize the covering on the core, a coolingtube connected to the exit end of the vulcanizing tube, means forcontinuously introducing low temperature water into the cooling tube ata pressure which permits a predetermined leakage of the steam into thecooling tube, said leakage of the steam into the water creating atemperature differential in the cooling water at opposite ends of thecooling tube which varies with fluctuations in the pressure differentialbetween the water and the steam, means for measuring differentials inthe temperatures of the cooling water at the opposite ends of thecooling tube, and a controller responsive to the temperaturedifferentials existing in the cooling water at opposite ends of thecooling tube as measured by said temperature diiertial measuring meansfor continuously maintaining the cooling water at a pressure whichpermits only the said predetermined leakage of the steam into thecooling tube.

i9. The process for the vulcanization of a vulcanizable coveringsurrounding a continuously advancing core, which comprises passing thecovered core continuously through an elongated treating zone, subjectingthe advancing core to a high temperature, high pressure vulcanizing uidwithin the portion of the treating zone lrst encountered by theadvancing core to vulcanize the covering thereon, subjecting theadvancing core to a low temperature cooling fluid within the nextsucceeding portion of the treating zone to 'cool Vthe vulcanizedcmfering;4 measuring the temperature diierentials between spacedpointsin the cooling'uid, and controlling therelative pressures ci the uids inaccordance with ,the measured temperaturediierentials existing betweensaid spaced points'in the cooling fluidV so as to maintain the pressuresof the cooling fluid and the vulcanizing fluid substantially equal.

20.` The process for the vulcanization of a vulcanizable coveringsurrounding a continuously advancing core," which comprises passing thecovered core through an elongated treating zone, introducing highpressure steam into the initial portion of the treating zone tovulcanize the covering thereon, introducing high pressure, lowtemperature water within the next succeeding portion of the treatingzone to cool the vulcanized covering, measuring the temperaturesprevailing at two spaced points Within the cooling water, andcontrolling the relative pressures of the steam and water in accordancewith the temperature differentials existing between the spaced 20 pointsin the cooling water at which said temperatures are measured so as tocontinuously maintain thecooling Water at a pressure substantially equalto the pressure of the steam.

GEORGE E. BERGGREN.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2,069,087Forstrom et al Jan. 26, 1937 2,291,344 Powell July 28, 1942 2,373,816 DeRoche et al Apr. 17, 1945 2,426,341 Canfleld Aug. 26, 1947 2,446,620Swallow et al Aug. 10, 1948 FOREIGN PATENTS Number Country Date 864,121France Jan. 8, 1941

